Process for treating oil



6, 1934. u, BRAY 1,949,989

PROCESS FOR TREATING OIL Original Filed July 7, 1950 W iizrzaace Crudeon! 1%; rsmzm 17 zamw 4 Wafer {/0 b e oarazbr 145Zvaporalr 146 fINVENTOR. Ulric Bfir'ay 50 143 ATTORNEY. JQS/QMC! Jforuya flea/MedUNITED STATES PATENT OFFICE PROCESS FOR TREATING 01L Ulric B. Bray,Palos Verdes Estates, Galif., as-

signor to Union Oil Company of California, Los Angeles, Calii.'., acorporation of California Original Application July 7, 1930, Serial No.466,189. Divided and this application July 29, 1932, Serial No. 625,584

19 Claims.- (Cl. 19613) This invention relates to a process for theproduction of lubricating oil. More specifically it relates to a methodof producing lubricating oil fromoil containing asphalt and is adivision of my patent application Serial No. 466,189, filed July '7,1930.

In the aforesaid patent application, filed by me on July 7, 1930, Ipointed out that the lubricating oil components of asphaltic crudecannot be separated from the asphalt by ordinary distillation methodswithout an impairment of the temperature viscosity susceptibility of theoil. The high temperature necessary for separation of the oil from theasphalt appears to render the .oil distillates more susceptible to achange in viscosity with a change in temperature than is characteristicoi the oil prior to its separation from the asphalt. mirthermore, in theclassification of oils according to their respective temperatureviscosity slopes I described oils which exhibited a low temperatureviscosity susceptibility as having a high percentage of parafin basecharacteristics and oils which exhibited a high temperature viscositysusceptibility as having a low percentage of pararhn basecharacteristics. In other words the parafdn base characteristics of anoil are those properties which cause its viscosity temperaturesusceptibility to resemble that ole. parafin base oil.

Since the separation of asphalt from the oil by distillation of the oilcannot be accomplished without destruction of the paradln base char-=acteristics of the oil, the process devised by me for removal of theasphalt comprises its precipitation by means 01 solvents. Asphalt may beprecipitated from oil by chemicals, such as sulfuric acid. I find,however, that it is best precipitated by use of solvents in which thelubricating oil fractions are soluble but in which the asphalt isinsoluble. Such solvents are alcohol, ether, mixtures of ether andalcohol, acetone, volatile hydrocarbon solvents, such as casingheadgasoline and light naphthas. I find, however, that the process is bestcarried out by the use 0! hydrocarbons which are normally in the vaporstate at atmospheric pressureand temperature. Such hydrocarbons includepropane, isobutane, butane, ethane, methane and mix tures thereof. Thesemay be obtained by rectification of casinghead gasoline by the so-calledstabilizing method now conventional in the natural gas industry. Theyare the overhead thus obtained. They are liquefied by compression andcooling in. the conventional manner and drawn off intopressure chamberswhere they are main-e tained in the liquid state until they are used. Atypical analysis of such a fraction is 6.72% ethane, 72.20% propane,19.91% isobutane and 1.17% normal butane and the necessary pressure tomaintain the fraction in aliquid state is approximately 125 lbs. persquare inch gauge at 73 F. This mixture has an average molecular weightsubstantially equal to propane. The oil stock containing asphalt ismixed with this liquid solvent under pressure, the mixture is allowed tosettle to permit the precipitation of the asphalt. The solution oflubricating oil in the liquid sol-= vent is withdrawn from the pressureprecipitator and expanded through heating coils to vaporize the solvent,leaving behind the liquid lubricating oil free of asphalt. The vaporsare recompressed and cooled to liquefy them and are then returned to thesystem. The lubricating oil traction produced may then be distilled atatmospheric pressure by conventional methods of distillation, such asthe tube still or the shell still with proper rectification orfractionatine equipment to produce any desired cut of lubricating oil.

Any contained was may be extracted and the oil treated with acid. Iprefer to distill the oil to leave a residue which contains thefractions having a viscosity above 400 to 50d seconds dew; boltUniversal at 100 F. In other-words, the degree of distillation shouldleave a residue such that if it were redistilled the first fractionstaken overhead would be about 600 to too smonds Saybclt'Universal at 108F. These figures are by their very nature approximate since they mustoverlap and the spread of the cut will be dependent on the percentagetaken overhead. This will result in a minimum deterioration of thedesireble temperature viscosity characteristics. Obviously the oil maybe more deeply topped, l. e., higher viscosity oils may be takenoverhead it a partial sacrifice oi those desirable qualities is notuneconomic. It is to be noted that the above criteria will hold both forbatch and for flash distillation within reasonable commercial it ispreferred to top the crude so as to leave be-= hind a residue which onextraction, as above.

leaves a lubricating oil of the desired visconty. However, the processmay be run as well by topping the crude as far as possible, i. e.,without injuring the paramn base characteristics, extracting the residueto remove the asphalt. treating the distillate and residue with acids,alkali and/orclay and then blending to the desired viscosity.

It is characteristic of this extraction process that the asphaltcontaining oil used for the extraction and the asphalt tree lubricatingoil produced have substantially the same paraffin base characteristics.In other words, the asphalt while it affects the absolute viscosity ofthe oil does not affect the variation of the viscosity with temperature,i. e., the slope of the temperature viscosity curve is unchanged. Thisis made possible by the fact that the present process removes theasphalt without afiecting the characteristic oils. All of the paraflinbase components present in the asphalt containing oil are foundunchanged in the extracted oil.

The following is a description of a preferred method for treating amixed base oil, 1. e., one containing asphalt and wax, wherein theasphalt is precipitated under conditions such as to leave the wax andoil in the propane solution. Advantage is taken of the propane solutionto permit a continuous acid treatment and alkali treatment of the oil.This is a particular advantage of this process since it permits rapidsettling of the sludge. The extreme volatility of the propane is used toact as a refrigerant to cause separation of the wax. The process will bemore particularly described by reference to the drawmg.

Referring to the drawing, the crude oil to be used asa source oflubricating oil is taken from the crude oil storage tank 1 and sentthrough coil 2 in furnace 3, whence it is sent to evaporating column 4.The temperature in coils 2 and 19 and the duration of heating in thestill sys tem, 2, 4, 1'7, 19 and 22, is so regulated that the amount ofconversion i. e., the destruction of inherent paraffin basecharacteristics is minimized. As a convenient criterion the temperatureshould not be raised beyond GOO-650 F. The vapors passing through 5,consisting of gas oil, kerosene and gasoline vapors, go to dephlegmator6 where they are fractionated into gasoline overhead and kerosene andgas oil bottoms, which may be re-run or handled in any conventionalmanner. The vapors pass through 'I, are condensed in 8, condensate, i.e., gasoline, is collected in 9. A part is returned through 10, todistributor 11, to act as a reflux. The dephlegmator bottoms passthrough 12, and are cooled in 13. These consist of gas oil and kerosene.Part is returned as a wash via line 14 and spray 15. The bottoms fromevaporator 4, consisting of oil containing lubricating fractions andasphalt, pass through the rundown line 16 to the hot residuum storagetank 17 which may serve only as a surge tank in the continuous operationof the process. The hot residuum from tank 17 is passed through pump 18which sends the hot residuum through coil 19 in furnace 20, where theresiduum is heated to about 625 F. Care is taken at this point not tooverheat the residuum because of the danger of injuring the quality ofthe lubricating oil to be obtained later, i. e., its paraffin basecharacteristics. The temperature to which the oil may be heated hasbeenadequately described above. The heated residuum passes tofractionating column 22. Steam,

superheated in coil 21, is introduced in column 22 to aid in theflashing of the volatile oils which are taken ofi in one or more sidestreams and as an overhead. The oil is fractionated by fractionatingplates 23 and a number of side streams are removed through lines 24controlled by valves 25, reflux is generated by means of a coolerpositioned at the top of the column. The various oils pass, throughvalve 26 and are cooled in 27 and collected in 28. If desired as manytanks as there are side streams may be employed. The s de streamdistillates may be processed in any suitable manner to produce desirableproducts. The

overheads from the column pass through line.29,

are condensed in condenser 30 and cooled in rundown tank 31. Uncondensedvapors are removed through 32, condensed oils composed of lightlubricating oils are removed through 33 and the condensed water removedthrough 34. The bottoms from column 22 are run through line 35 by meansof pump 35a to cooler 36 from which it is' delivered to the toppedresiduum tank 37. The operation of coil 19 and column 22 is so regulatedas to produce the predetermined extent of topping necessary to give theproper viscosity oil in the later extraction with propane. The toppedresiduum stored in tank 3'1 is sent by pump 38, meets liquid propanecontaining a small amount of oil coming through line 45. The preferredfraction is that obtained as an overhead in the stabilization of naturalgas gasoline as previously mentioned. The mixture of propane andresiduum pass through mixing coil 39 into decanter 40, where the asphaltin the topped residuum is precipitated and settles rapidly as a slurry.From the bottom of decanter 40, the asphalt slurry is pumped by pump 41to meet fresh liquid propane introduced by pump 46 via line 47 frompropane storage 48. The asphalt slurry and fresh liquid propane are sentthrough mixing coil 42 into decanter 43. The asphalt propane slurry fromthe bottom of decanter 43 is drawn off through line 145, and valve 146and discharged at a lower pressure into a still, as will be discussedhereafter.

The overflow from decanter 43, containing the oil and wax is sent bypump 44 through line 45 to be mixed with the topped residuum and sentinto decanter 40, as explained above. The over flow from decanter 40consisting of propane and lubricating oil stock in the desired ratio issent through pump 51 for the acid and alkali treatment of the extractedlubricating oil stock. The countercurrent washing of the precipitatedasphalt illustrated by the above method of operation may be extended toas many steps as desired, but in general two decanters giving twocountercurrent washings will be suliicient to produce an asphaltsatisfactorily free of wax and oil.

To the propane solution of extracted lubricating stock, acid from tank52 is added to mixer by means of pump (or acid egg) 53, and the flow iscontrolled also by valve 54. The propane solution and acid are forced bypumps 51 and 53 through mixing coil 55 into decanter where the acidsludge settles rapidly. The addition of the acid in several dumpswithout drawing the sludge between dumps may be accomplished by tappingmixing coil 55 at various points and introducing acid at these points.The addition of acid in several dumps with the withdrawal of sludgebetween dumps may be accomplished by means of additional mixing coilsand acid decanters. The acid treated oil solution from decanter 60 flowscontinuously through line 62 into decanter 63, where water is introducedas a spray through line 68 from water storage 64 through pump 65 andvalve 67 and acid reaction products are withdrawn through line 56controlled by valve 57. The-water washed oil overflows from decanter 63and is sent by pump 69 to be treated. Water is withdrawn via line 58controlled by valve 59. The soda solution contained in tank 70 isintroduced by pump '71 through line '72 controlled by valve 73. Themixture of oil solution and aqueous alkali solution is forced throughmixing coil 74 into decanter 75 where the caustic solution separatesfrom the propane solution of the oil, and is withdrawn through valvedline 76. The overflow from decanter 75 goes through line 77 to decanter78, where water is introduced through spray 79 by means of pump 65through valve 66. The separated water wash is withdrawn through valvedline 80. The use of propane as a solvent permitsthe continuous and rapidtreatment of lubricating stock in the manner just described.

The neutralized and water washed oil solution overflowing from decanter78 is carried by line 81 to tank 82, the latter acting as a reservoir orsurge drum between the acid treating and dewaxing operation.

Treated oil solution in tank 82 is sent through valve 83 and line 84 toline 86 or 92 where it is sent into low pressure column -87 or lowpressure column 94 by the proper operation of valves and 93. Consideringvalves 91 and 93 closed and valves 85 and open, the propane solutionflows into low pressure column 87. Valves 85 and 93 are pressurereducing valves' separating the low pressure columns 87 and 94 from thehigh pressure treating and decanting vessels. In low pressure column8'7, suflicient propane vaporizes to reduce the temperature of theremaining material to a predetermined dewaxing temperature. The desireddewaxing temperature is obtained by controlling the pressure in column37 by the proper operation of valve 90 and propane compressor 103, whichis connected to the evaporator by line 102. The pressure to bemaintained in column 87, as shown by gauge 89, will be, generally, about0 lb. gauge which corresponds to a temperature of approximately -40 F.

As the propane solution passes through valve 85, its pressure is reducedso that a portion of the propane evaporates in column 87 and the vaporspass out of the .top, through mist extrac tor 87a through line 88controlled by valve 90. The solution from tanlr 82 continues to flowinto column 37 until a predetermined quantity has accumulated. Valves 85and 99 are then closed and valve 93 opened. Production then flows intocolumn 94 until the predetermined quantity of solution has passed intothe second column. The propane'is vaporized, passes "through mistextractor 95 through line 98, valve 98 being controlied so that theproper reading is obtained on gauge 97. In the meantime, the vaporpressure of the propane in column 87 has been reduced to approximately 0lb. gauge by the operation of valve 99 and propane compressor 103,thereby reducing the temperature or the material remaining in column 87to approximately 4il F. When this temperature is reached in column 87,valve 91 is opened and the cooled material is passed through line 1110,pump 101 and valve 108 into the gas tight centrifuge 107 in box 199.Motor 108 is for the centrifuge. The centrifuge is of conventional type.The dewaxed propane solution of lubricating oil discharged from thecenter of the centrifuge through line 121 is sent by pump 122' throughvalved line 123 and heat exchanger 12%.

In passing through heat exchanger 124, heat isheat required forvaporization of the propane by fire rather than by steam, the propanesolution may be passed through coil 129 in furnace 130 by the propermanipulation oi. valves 126,

127 and 131 into evaporator 132. Open steam is introduced intoevaporator through 133 to complete the vaporization of the propane andto reduce the oil to satisfactory flash and fire specifications. Ingeneral, however, the tunction of the steam will be to complete thevaporization of the propane. The vapors passing through the mistextractor 134 pass from the top of evaporator 132 through heat exchangercoil 135 where water is condensed by the cold propane solution oflubricating oil coming from the centrifuge. Leaving heat exchanger coil135, the condensed steam and any light oil removed from evaporator 132pass into separator 136' with the uncondensed propane vapors; Theuncondensed propane vapors leave the separator 136 through line 139 andpass to line 140 from which they enter, the' suction of propanecompressor 144 to be compressed and sent through line 104 to propanecooler where the propane vapors are liquefied and returned to propanestorage 48. Light lubricating oil is removed through 138 and waterremoved through 137. The bottoms from evaporator 132, consisting ofthetreated and dewaxed oil, are drawn 011 by pump 141 and passed throughheatexchanger coil 142 where heat is imparted to the water used to meltthe wax in the wax discharge line from the centrifuge, as will be laterdescribed. vLeaving heat exchanger 142. the treated and dewaxed oilpasses into storage tank 143.

The wax discharged from the centrifuge .through line is mixed with warmwater, at

about 140 F. .The melted wax and water pass into separator 111 and thewax is withdrawn through line 112 to wax storage 113. The water fromseparator- 111 is passed through line 114 to water storage tank and thenthrough line 116, pump 11'? andline 118 to heat exchanger coil 119 whereit is heated by the bottoms from evaporator 132, as explained above. Thewarm water leaving heat exchanger coil 119 is passed through line toline 110 to complete the cycle. The vapors from the top of separator111, consisting of propane discharged with the wax from the centrifuge,are conserved by compressing and returning to high pressure propane line104 going to propane cooler 185 by passing through line I 1120; intoline 149 and compressor 14 1. The vapor space in the gas tightcentrifuge should be connected with the suction of a propane compressordischarging into the high pressure propane system. Provision for thislatter conservation of propane ismade by connecting either the dewaxedoil discharge line 121 or the wax discharge line 116 with the gas spacein the centrifuge, as willbe understood by those skilled in the art.

-The asphalt material from separator 43 is passed through line 145,flashed through valve 146 and heating coil 147 in furnace 148 andpressure reduction valve 149 into evaporator 151, which operates'at alower pressure. Steam superheated in coil156 is introduced into 151 tosupply additional heat and to reducethe asphalt to properspecifications, generally only as regards flash-and flre points. Theasphalt is taken from the bottom of the evaporator 151 and sent throughthe valved rundown line 159 to asphalt .storage 160. The overhead fromevaporator 151 passing through mist extractor 152 is sent through line153, to cooler 154, and then to separator 155. The uncondensed propanefrom separator 155 is sent through line 157 to line to high pressure vssels containing liquid propane to a pressure equalizing line 49controlled by valve 50, as shown in the drawing. Without provision forequalizing the pressure in the different vessels, flow of liquid will becontrolled entirely by pump pressure.

In the operation of the centrifuges, it is desirable to maintain ahigher pressure upon the propane, oil, wax mixture than corresponds tothe vapor pressure of the mixture at that temperature. The reason forthis increased pressure is to prevent foaming or gas evolution in theliquid. This pressure is applied by pump 101. If it is desirable tooperate the centrifuge at atmospheric pressure or at only slightlyincreased pressure, the pressure maintained in cooling column 87 or 94before the liquid in that column is sent to the centrifuge should beless than atmospheric pressure, so that when the pressure is raised toatmospheric before passage through the centrifuge, the liquid may warmup several degrees without boiling or foaming.

Evaporator 132 may be operated at a sufficiently high pressure to causeliquefaction of the propane vapors when cooled, and in this mannereliminate the use of a compressor on the vapors from the top ofseparator'136. When operating column 132 at high'pressure, pump 122 isoperated at a higher discharge pressure and heat exchanger 124 isoperated so as to cause condensation of only steam and oil vapors.

The above description is merely illustrative of one mode of employing myinvention and is not to be construed as limiting as many variations willappear to those skilled in the art within the scope of my inventionwhich I claim to be:

1. A process for separating asphalt from oil containing same whichcomprises'washing precipitated asphalt with fresh solvent to dissolveresidual oil from said precipitated asphalt and mixing the solution ofresidual oil and solvent with fresh oil containing asphalt to producethe aforementioned precipitated asphalt.

2. A process for separating asphalt from oil containing samewhichcomprises mixing asphalt containing oil with a solvent to precipitateasphalt, separating the precipitated asphalt from the solution of oiland solvent, mixing the precipitated asphalt with a liquefied normallygaseous hydrocarbon solvent to separate residual oil.

and employing the solution of residual oil and solvent as the solvent toprecipitate the asphalt from the asphalt containing oil first mentioned.

3. A method for separating asphalt from an oil containing asphalt whichcomprises extracting said oil with a normally gaseous liquid hydrocarbonsolvent a major portion of which solvent consists of hydrocarbons ofless than four carbon atoms to cause a separation of the asphalt andseparating the asphalt from the oil dissolved in said hydrocarbonsolvent.

4. A method for separating asphalt from oil containing asphalt whichcomprises extracting said oil with a normally gaseous liquid hydrocarbonsolvent, the major portion of which solmaintain said hydrocarbon liquidand at a temperature sufliciently elevated to dissolve the oil in saidhydrocarbon solvent and to separate asphalt and separating the oildissolved in said hydrocarbon solvent from the separated asphalt under.superatmospheric pressure.

7. A process for separating asphalt from oil containing asphalt, whichcomprises commingling the oil with a normally gaseous hydrocarbonsolvent, consisting of a major proportion of hydrocarbons of less thanthree carbon atoms, under superatmospheric pressure suflicient tomaintain said hydrocarbon liquid and at a temperature sufficientlyelevated to dissolve the oil in said hydrocarbon and to separate asphaltand separating the oil dissolved in said hydrocarbon solvent from theseparated asphalt.

8. A process for separating asphalt from oil containing asphalt, whichcomprises commingling the oil with a normally gaseous hydrocarbon, themajor proportion of which is propane, under superatmospheric pressuresufficient to maintain said hydrocarbon liquid and at a temperaturesufficiently elevated to dissolve the oil in said hydrocarbon, toseparate asphalt and separating the oil dissolved in said hydrocarbonsolvent from the asphalt.

9. A process for separating asphalt from asphaltic oil which comprisescommingling the oil with a normally gaseous hydrocarbon solvent, themajor portion of which consists of propane and ethane and undersuperatmospheric pressure suflicient to maintain said hydrocarbonsolvent liquid and at a temperature sufliciently elevated to dissolvethe oil in said hydrocarbon, and to separateasphalt and separating theoil dissolved in said hydrocarbon from the separated asphalt.

10. A process for separating asphalt from oil containing asphalt, whichcomprises commingling the oil with propane under superatmosphericpressure sufllcient to maintain said propane liquid to dissolve the oilin said propane and to separate asphalt and separating the oil dissolvedin said propane from the separated asphalt.

11. A method for separating asphalt from oil containing asphalt whichcomprises commingling said oil with ethane undersuperatmosphericpressure sumcient'to maintain said ethane liquid todissolve the oil in said ethane and to separate asphalt and separatingthe oil dissolved in said ethane from the separated asphalt.

12. A method for separating asphalt from asphaltic oil containingasphalt which comprises extracting said oil with a liquid hydrocarbonsol- 'vent at least as volatile as propane to separate .solvent, havingan average molecular weight less than butane to separate asphalt andseparating aeaaeeo the asphalt from the oil dissolved in said solvent.

14. A method for separating asphalt from asphaltic oil containingasphalt which comprises commingling said oil with a hydrocarbon solvent,containing suficient hydrocarbons of less than three carbon atoms tomake the hydrocarbon solvent more volatile than butane, to separateasphalt and separating the asphalt from the oil dissolved in saidhydrocarbon.

15. A method of separating asphalt from an oil containing asphalt whichcomprises extrz ting said oil with a liquid hydrocarbon solvent having avapor pressure greater than butane to separate asphalt and removing theasphalt from the oil dissolved in said solvent.

it. A method for separating asphalt from an oil containing asphalt whichcomprises extracting said oil with a normally gaseous hydrocarhonsolvent consisting of a major proportion of hydrocarbons of less thanfour carbon atoms, to cause separation of the asphalt separating theasphalt from the oil dissolved in said hydrocaroon solvent andchemically treating the oil dissolved in said liquid hydrocarbon tofurther refine the oil.

1'7. A process for separating asphalt from oil gling said oil with anormally gaseous hydrocarbon under superatmospheric pressure suficientto maintain said hydrocarbon liquid and at a temperature sufficientlyelevated to dissolve the oil in said hydrocarbon solvent and to separate asphalt, separating the oil dissolved in said hydrocarbon solventfrom the separated asphalt and chemically treating the oil dissolved insaid hydrocarbon solvent to further refine the oil,

18. A method for separating asphalt from an asphaltic oil whichcomprises extracting said oil with a liquid hydrocarbon solvent, themajor por tion of which is propane, to separate asphalt, separating theasphalt from the oil dissolved in said hydrocarbon solvent andchemically treating the oil dissolved in said hydrocarbon solvent tofurther refine the oil.

19. A process for separating asphalt from oil containing asphalt whichcomprises connningling the oil with propane under superatmospheriopressure sufficient to maintain said propane li uid to dissolve the oilin said propane and to se, arate asphalt, separating the oil dissolvedin said propane from the separated asphalt and chemically treating theoil dissolved in said propane to further refine the oil.

ULREC B. BRAY.

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